hi mrfijjitt, darren has covered every base, very good suggestions!

if i was dealing with it- after a soaking in release oil try the over sized allen key trick if it failed, next the grips, then resorting to welding a bolt to the damaged fitting using a mig welder let it cool for a minute or so and then loosen, drastic sounding i know but between the direct heat and a decent grip it's the most effective

the fitting is basically a nut shaped like a sleeve, driven by a allen key. the stud coming out of the head allows for a strong reliable fitting. so i would avoid changing to a bolt style which can be more easily pulled out from the head causing worse problems, get on to yamaha and get new allen nut jobbies and new studs if nessasary

bernard